View Full Version : Charging System Problems

03-10-2016, 09:26 PM
I recently changed from long tube headers to short engine swap headers that would allow the exhaust to hang a little lower and clear the frame rails. Since the change, I now have starting issues. Prior to the swap the engine would fire and after a little coaxing would idle on its own. Now it acts as if the battery is bad. I had it checked and was told that the battery is fine. I took the starter in and was told it was okay as well. Today, while trying to track down the problem, I notice smoke rising from the throttle linkage while I was trying to start the car. The linkage was hot enough that I got a nice little blister on one of my fingers when I checked to see what was getting hot. Has anyone run into this kind of thing before? I have checked for wires that could be in contact with the linkage, but have found nothing. Any advice would be appreciated.

Jeff W
03-10-2016, 10:35 PM
I think this is an easy one. Check the large braided engine to chassis ground strap. On my little six is is on one of my starter bolts to the firewall. Sounds like it is trying using your throttle linkage for a poor ground. Maybe you took one end off during your header work.

A quick test would be to use a battery jumper cable for a temporary ground between some thing like a manifold bolt and your negative battery post.

I like your car, and the picture is great. How did you get the reflection on the floor and the white background?

03-11-2016, 08:57 AM
Thanks. The photo was taken at the Volo Auto museum in Volo, IL. Indoors of course with high gloss floors. They do a great job photographing vehicle they offer for sale and in their displays. This morning when my Son stopped by, he noticed spark arcing from the throttle linkage to the manifold. Definitely have a short somewhere near the firewall. There is very little that is stock about this Falcon. The overall body and the majority of the interior are stock but nothing else. It now sports a very healthy 408 Stroker backed by a MDL 5 Speed and 9 inch rear with 3.50 gears.

Jeff W
03-11-2016, 02:07 PM
he noticed spark arcing from the throttle linkage to the manifold.

I really think that "spark" is the return electricity from your srater motor trying to find it's way back to ground.

Try the jumper cable test to be sure the engine is grounded. If that isn't it I will eat my hat (and it's a very nice hat).

Also - when I said "easy" I didn't meant easy to diagnose - I meant easy to fix.

I can thank BPVan for helping me discover the ground strap issue. I was helping him on his Mercedes wagon a few months ago and we thought it was a bad starter. Smoke was literally rolling off of the braided stainless exhaust coupler and it burned his arm. We had forgotten to reattach the engine ground strap when replacing the transmission.

03-13-2016, 05:48 PM
You were right. The 302 I took out of the Falcon did not have a ground strap of any kind. So I tried to run the 408 without one. Not a good idea. I borrowed the negative cable off my lawn mower and ran it from the block to the firewall and all is well. I'll have to see if I can find an actual ground strap tomorrow. The car still acts like it needs more battery when trying to restart it after it has come to operating temperature. Thanks for your expertise, I really appreciate it.

Jeff W
03-13-2016, 08:56 PM
Glad it is solved. Six months ago I wouldn't have known the answer. Nice to know at 49 years old I can still learn and remember.

03-14-2016, 09:31 AM

You never mentioned... is the battery in the engine compartment or the trunk? Technically you have your battery ground lead connected directly to the engine, and the positive lead to the solenoid and a cable from there to the starter. If you have a high-torque starter the positive lead would go from battery directly to the starter - since the solenoid is on the high-torque starters. This assures the high-current demand of the starter is always seeing the large battery cables. The firewall strap should have zero bearing on the starting of the car. If it does, you've got to investigate your cable routing.

The problem also comes when the battery is in the trunk. It's not uncommon to use the frame of the car as a ground (back near the trunk) and then run the positive cable all the way forward. If you don't also run a cable from the frame to the engine up front, the high-current will try to use any path it can find, be it through leaf springs, driveline, transmission, shift linkage, anywhere it can find, to allow the higher starting current to flow.

The typical firewall ground-strap was NOT intended for this need. Way too small. Its purpose was to make sure the body got a good ground since the ground strap was connected to the engine. The small firewall cable was the path to ground for all the instrument lights, etc., was the body. Low current demands. You didn't want all you peripheral lights and instruments to find its path to ground through the leaf springs, transmission, shift linkage, anywhere it can find a path, anymore than you did the starter.

Though I know you said adding the mower cable helped, I would still push towards tracing cables from the battery to the starter and engine block. These should be good, large, and singular in purpose.

03-14-2016, 09:41 AM
The ONLY bearing the firewall ground strap has on the starting of the car (normal starter solenoid on the fender apron) is to allow the starter solenoid to find ground. It doesn't have the high-current demands of the starter, but it needs a good path to ground. If the solenoid is on the starter, like with a high-torque starter, the firewall ground strap would maybe allow it to work, but would prove a bad battery to engine "starter ground", which should be a good-sized cable.

A bad body ground can also affect the things mounted to the body that need power to start. This might be aftermarket or electronic ignition parts, etc.

03-26-2016, 02:56 PM
I ended up running a new ground cable from the trunk to the lower mounting bolt on the starter. Ran another ground from the block to the core support. The engine starts great cold, but will not turn over fast enough when hot to fire. I put a reduction gear starter on it and that seems to have solved the problem. Thanks to you guys for your recommendations.

03-28-2016, 09:31 AM
Sounds like heat-soak on the starter. On a 351 I did recently the car had a reduction starter and even adding a blanket it still has some hot-start issues. Heat increases resistance, but I think it has ground issues too. Last suggestion to the owner, which we'll do soon, is to add sub-frame connectors and then this will be used as a better path of ground from the trunk (battery there too) to the front.

It needed sub-frame connectors to handle the torque this car makes - so it was not the fix for the start issue. Just going to make-use of them to kill two (poor, unsuspecting, didn't deserve it) birds with one stone.